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Monday, July 31, 2017

Man, is it hot out there! While I tuck away in my cool, air-conditioned office, I think about those incredible animals that beat the heat with their own bodies and strategies. It turns out, there are only four major ways to exchange heat with your environment: conduction, convection, radiation and evaporation. The animals that are best equipped for a hot summer are those that take creative advantage of these mechanisms of heat transfer.

"My, what big ears you have!"
"The better to thermoregulate with, my dear!"
Photo by Bernard DUPONT at Wikimedia Commons.

We all exchange heat with our environment wherever our body comes in contact with the environment, namely, across our skin. Animals can increase the rate of this heat-exchange by having a larger surface area relative to the volume of their heat-containing bodies. Big, round animals have a particularly hard time dispersing excess heat, because they have a lot of heat stored in their big bodies, and proportionally not much surface area for the heat to leave from. You may think elephants have such big ears for hearing, but the truth is that they are major temperature-regulation organs. Big, flat body structures provide that added surface area for excess heat to dissipate from. Elephants have large ears with lots of large blood vessels, so they can pump hot blood from the body out to the ears, where they are closer to the cooler environment to dissipate by conduction and convection. The cooler blood then returns to the body core to cool it down.

Built for a life in the cool underground.
Photo by Ted M Townsend at Wikimedia Commons.

Reptiles use a different approach to take advantage of principles of conduction and convection, by burrowing. Burrows create a layer of insulation (usually soil and plant matter) that slows heat exchange and keeps the area below ground a more constant temperature. This means that, compared to the outside, burrows remain cooler in the summer and warmer in the winter. Many reptiles go into their summer burrow in the heat of day and emerge during cooler times of day. Blind lizards, however, take this burrowing idea to an extreme. Blind lizards are a family of legless lizards found in tropical forests. They are small, skinny, and have narrow heads, which make them look more like an earthworm than a lizard, but it also gives them great burrowing efficiency to stay underground and avoid the heat.

A dragonfly exposing as little of his body to the sun
as possible. Photo by Raphael Carter at Wikimedia Commons.

On a hot summer day, we all seek out the shade. This is to reduce the heat we absorb through radiation, and most of this radiation comes from the sun. But what do you do if you can’t find shade? Some dragonflies and damselflies raise their abdomens to aim their rear-ends towards the sun so they can shield themselves from the full-on intensity of the sun’s rays. This body position is called the obelisk posture, because when the sun is directly overhead, the insect’s handstand looks like an obelisk.

Really? Crapping on my own feet?
There has GOT to be a better way.
Photo by Rob Schoenmaker at Wikimedia Commons.

Evaporation is the most efficient way to dissipate heat. Some animals swim, some animals sweat, some animals pant, but vultures and storks win the cooling efficiency award. Vultures and storks. . . poop on their own legs and feet. With this approach, called urohydrosis, the animal releases a mixture of urine and poop through their single excretory hole, called a cloaca, onto their legs and feet. The subsequent evaporation from the high surface area of their long legs helps them to cool off.

So what can we learn from these heat-beating experts (without pooping on ourselves)? If you are hot, spread your body out, stay in the shade, and wet an area of your body with high surface area and exposed blood vessels (namely, your inner wrists and forearms). I’d use water though.

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Miss Behavior’s real name is Sarah Jane Alger and she is a biologist and student of life. Friend/Follow her on Facebook and/or Google+ (look for this picture) to get updates on The Scorpion and the Frog.